Use Drive v2 API: enable behind --enable-drive-api flag

chrome/browser/chromeos/gdata/gdata_file_system.h

Index: chrome/browser/chromeos/gdata/gdata_file_system.h
diff --git a/chrome/browser/chromeos/gdata/gdata_file_system.h b/chrome/browser/chromeos/gdata/gdata_file_system.h
index c5c2503315b18bcc5ca0e06512ef175b5b98dddd..0abccf729dee1076ad0f4d327600b2b68d74b71f 100644
--- a/chrome/browser/chromeos/gdata/gdata_file_system.h
+++ b/chrome/browser/chromeos/gdata/gdata_file_system.h
@@ -147,7 +147,7 @@ class GDataFileSystemInterface {
 
   // Initializes the object. This function should be called before any
   // other functions.
-  virtual void Initialize() = 0;
+  virtual void Initialize(bool use_drive_api) = 0;
 
   // Adds and removes the observer.
   virtual void AddObserver(Observer* observer) = 0;
@@ -401,7 +401,7 @@ class GDataFileSystem : public GDataFileSystemInterface,
   virtual ~GDataFileSystem();
 
   // GDataFileSystem overrides.
-  virtual void Initialize() OVERRIDE;
+  virtual void Initialize(bool use_drive_api) OVERRIDE;
   virtual void AddObserver(Observer* observer) OVERRIDE;
   virtual void RemoveObserver(Observer* observer) OVERRIDE;
   virtual void StartUpdates() OVERRIDE;
@@ -1271,6 +1271,9 @@ class GDataFileSystem : public GDataFileSystemInterface,
 
   // The token is used to post tasks to the blocking pool in sequence.
   const base::SequencedWorkerPool::SequenceToken sequence_token_;
+
+  // If true use Drive v2 API instead of Document List API.
+  bool use_drive_api_;
 };
 
 }  // namespace gdata